JP2001114087A - Traveling control device for industrial vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrict the slip of a driving wheel in relation to a road surface when operating a brake during the traveling while automatically operating a clutch with a torque converter. SOLUTION: When a brake pedal 33 is operated during the forward traveling of a vehicle, a controller 45 switches the clutch pressure Prcl of a backward clutch 22, which is not selected by a shift lever 37, from '0' in the cutting condition to the initial brake clutch pressure set in response to the brake operating force and a load W. When the rotating acceleration α found on the basis of the rotating speed of a front wheel 14 is less than the preset rotating acceleration determining value α 0, the clutch pressure Prcl is switched from the initial brake clutch pressure to '0'. When the rotating acceleration α exceeds the rotating acceleration determining value α 0, the clutch pressure Prcl is switched from '0' to the brake clutch pressure Prcl smaller than the initial brake clutch pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of inputting a driving force of an engine to a transmission via a torque converter, and switching forward and backward clutches provided in the transmission to move forward and backward. The present invention relates to a travel control device for an industrial vehicle such as a forklift.

[0002]

2. Description of the Related Art An example of such a traveling control device for an industrial vehicle is disclosed in Japanese Patent Application Laid-Open No. 10-151974. A vehicle equipped with this travel control device can basically be operated only by operating an accelerator pedal, a brake pedal, and a direction switching lever. Since it is not necessary to operate the clutch pedal, which requires a delicate operation, so that the applied acceleration does not suddenly change and the load collapses, the driving operability can be improved.

In such a travel control device, the driving force of an engine is input to a transmission via a torque converter in which a rotation speed ratio between an input shaft and an output shaft automatically changes according to a load on an output shaft. As a result, the final reduction ratio is changed within a predetermined range, and traveling that does not generate an impact at the time of starting or the like is enabled.

[0004]

By the way, industrial vehicles such as forklifts have a greater weight on tires than ordinary passenger vehicles. Therefore, when the driving wheels slip on the road surface during braking, the driving wheels become unevenly worn. And tire marks are easily attached to the road surface.

[0005] Therefore, when braking the vehicle, an anti-lock brake (ABS) such as that used in general passenger vehicles is used.
By performing the control, it is conceivable to make the drive wheels hard to slip on the road surface.

However, in a general passenger vehicle, anti-lock brake control is performed by controlling an ABS actuator provided on an oil passage between a wheel cylinder that operates a wheel brake and a mast cylinder that is operated by a brake pedal, using an ABS computer. ing.
Therefore, if such an antilock brake device is newly provided in both industries, the ABS actuator and the ABS
There is a problem that the number of components increases and the number of assembling steps increases due to the computer.

[0007] The above-mentioned problems are not limited to forklifts, but are common to other industrial vehicles having the same traveling control device. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to make it unnecessary to operate a clutch pedal and to automatically perform a clutch connection / disconnection operation by a switching operation of a direction switching operation member. It is another object of the present invention to provide a travel control device for an industrial vehicle that can suppress a slip of a drive wheel on a road surface during braking without increasing a number of new components.

[0008]

According to an aspect of the present invention, there is provided a torque converter to which an engine driving force is input, and an engine driving force input through the torque converter. A transmission that outputs the driving force via one of a forward clutch and a reverse clutch, the connection state of which is adjusted by changing the clutch pressure; and connecting either one of the two clutches. Direction detecting means for detecting a switching position of a direction switching operating member which is switched to disconnect the other, and provided for each of the clutches, and controlling the clutch pressure to disconnect the connected state of the clutch from the completely connected state. A traveling electromagnetic pressure control valve for adjusting between the state and the state, controlling each traveling electromagnetic pressure control valve according to the switching position, controlling the clutch pressure, In a traveling control device for an industrial vehicle including a clutch control unit for completely connecting or disconnecting a clutch, a brake unit capable of braking the vehicle with a braking force corresponding to a brake pressure of supplied hydraulic oil, and adjusting the brake pressure Electromagnetic pressure control valve for braking, brake operation force detection means for detecting a brake operation force when the brake operation member is operated, and drive rotationally driven by the drive force output from the transmission A driving wheel rotational speed detecting unit that detects a rotational speed of a wheel, a rotational acceleration calculating unit that sequentially calculates a rotational acceleration of the driving wheel from the driving wheel rotational speed, and a brake operating force based on the brake operating force. The brake pressure is controlled via the braking electromagnetic pressure control valve so that the larger the greater, the greater the braking force is applied to the braking means. In both cases, when the rotational acceleration is less than a rotational acceleration determination value set in advance to determine a slip state of the drive wheel with respect to the road surface, the braking force of the brake means is smaller than the braking force based on the brake operating force. And a brake control means for controlling the brake pressure.

According to a second aspect of the present invention, in the traveling control device for an industrial vehicle according to the first aspect, the brake means is a switching position of the direction switching operation member among the forward clutch and the reverse clutch. , The braking electromagnetic pressure control valve is the traveling electromagnetic pressure control valve that controls the clutch pressure of the clutch.

According to a third aspect of the present invention, in the traveling control device for an industrial vehicle according to the first aspect, the brake means is provided separately from the forward and reverse clutches to brake the rotation of the drive wheels. A parking clutch brake capable of restricting the movement of the vehicle, wherein the electromagnetic pressure control valve for braking is provided separately from the electromagnetic pressure control valves for traveling, and controls a brake clutch pressure of the parking clutch brake. adjust.

According to a fourth aspect of the present invention, in the travel control device for an industrial vehicle according to any one of the first to third aspects, the brake control means is provided when the vehicle speed is set to a predetermined low speed. In the state where the rotational acceleration is equal to or less than the braking determination value, the brake pressure is controlled even when the rotational acceleration is less than the rotational acceleration determination value, as in the case where the rotational acceleration is equal to or greater than the rotational acceleration determination value.

According to a fifth aspect of the present invention, in the travel control device for an industrial vehicle according to any one of the first to fourth aspects, the brake control means is configured to determine that the rotational acceleration is the rotational acceleration determination value. When it becomes less than the above, the brake pressure is a non-braking brake pressure for bringing the brake means into a non-braking state, and when the rotational acceleration again becomes equal to or more than the rotational acceleration determination value, the brake pressure is
The brake pressure corresponding to the brake operation force is at least as large as the magnitude corresponding to the added value of the deviation of the rotational acceleration from the rotational acceleration reference value when the rotational acceleration is less than or equal to the rotational acceleration determination value that is equal to or greater than the rotational acceleration determination value. Than the non-braking brake pressure.

According to a sixth aspect of the present invention, in the traveling control device for an industrial vehicle according to the fifth aspect, the rotational acceleration reference value is set according to a setting state for setting a deceleration during braking. Speed setting means is provided.

According to a seventh aspect of the present invention, there is provided the traveling control device for an industrial vehicle according to any one of the first to sixth aspects, further comprising a load detection unit for detecting a load.
The brake control means, so that the brake means brakes with a larger braking force as the loading load is larger,
While controlling the brake pressure through the braking electromagnetic pressure control valve, when the rotational acceleration is less than the rotational acceleration determination value, the braking force of the brake means,
The brake pressure is controlled so as to be smaller than the brake operation force and the braking force based on the loaded load.

According to an eighth aspect of the present invention, in the travel control device for an industrial vehicle according to any one of the first to seventh aspects, the brake operation member is operated by a brake operation, and A wheel brake is provided for braking the drive wheels with a braking force according to a brake operating force, and the brake means brakes the vehicle in cooperation with the wheel brake.

(Operation) According to the first aspect of the present invention,
When the brake operation member is operated, the brake pressure of the brake means is controlled, and the drive wheels are braked with a braking force having a magnitude corresponding to the brake operation force. When the drive wheel, the rotation of which is limited by braking, slips on the road surface at a predetermined slip ratio or more, the rotational acceleration of the drive wheel becomes less than the predetermined rotational acceleration. When the detected rotational acceleration is less than the predetermined rotational acceleration determination value, it is determined that the drive wheel is slipping on the road surface at a predetermined slip ratio or more.
Then, the brake pressure is controlled based on the fact that the rotational acceleration is less than the rotational acceleration determination value, and the braking force by the brake means is at least smaller than the magnitude with respect to the brake operating force. Therefore, while the vehicle is braked by the brake means, the braking force of the brake means is limited while the drive wheel slides on the road surface at a predetermined slip ratio or more during braking.

According to the invention described in claim 2, according to claim 1
In addition to the effects of the invention described in (1), the vehicle is braked during traveling by the clutch that does not transmit the driving force during traveling of the vehicle, of the forward clutch and the reverse clutch.

According to the invention described in claim 3, according to claim 1 of the present invention,
In addition to the effect of the invention described in the above, the vehicle is braked from running by the parking clutch brake that regulates the movement of the vehicle by braking the rotation of the drive wheels.

According to the invention described in claim 4, according to claim 1,
In addition to the functions of the invention according to the third aspect, when the vehicle is braked by the brake means and the vehicle speed is reduced to be equal to or less than a predetermined low-speed braking determination value, the momentum of the vehicle is reduced, so that the brake means As a result, a change in the acceleration applied to the vehicle due to a change in the braking force applied to the vehicle increases. In this state, if control is performed to limit the braking force by the brake means based on the fact that the rotational acceleration is less than the rotational acceleration determination value, the vehicle immediately before stopping may be jerky. Here, in a state where the vehicle speed becomes equal to or lower than the predetermined low-speed braking determination value due to braking, even if the rotational acceleration becomes less than the acceleration determination value, the brake pressure is controlled in the same manner as when the rotational acceleration is equal to or more than the acceleration determination value. The vehicle does not jerk just before stopping.

According to the invention described in claim 5, according to claim 1,
In addition to the effect of the invention according to any one of claims 4 to 6, braking is released when the slip ratio of the driving wheel to the road surface exceeds a predetermined value during braking, and the braking of the driving wheel is performed by releasing the braking. When the slip rate falls below a predetermined value,
The sliding state of the drive wheel when the braking is released is continued for a long time, or the braking is performed with a smaller braking force as the sliding rate increases. Accordingly, the braking force of the braking means is controlled so as to perform braking while reducing the degree of slip according to the degree of slip of the drive wheel during braking.

According to the invention of claim 6, according to claim 5,
In addition to the operation of the invention described in the above, if the rotation acceleration reference value is set to a value larger than the rotation acceleration determination value according to the setting state for setting the deceleration during braking, the rotation of the rotation acceleration The added value of the deviation from the acceleration reference value increases. Then, when the rotational acceleration is equal to or greater than the rotational acceleration determination value, the braking force by the brake means is made smaller. Accordingly, the braking force is controlled such that the degree of slippage of the drive wheels during braking is adjusted according to the set state.

According to the invention of claim 7, according to claim 1,
In addition to the effect of the invention according to any one of claims 6 to 6, when the brake operation member is operated by a brake, a brake means whose brake pressure is adjusted according to the brake operation force and the loaded load, The driving wheels are braked by a braking force having a magnitude corresponding to the brake operation force and the loaded load. Therefore, a change in the deceleration of the vehicle with respect to the brake operating force of the brake operating member with respect to a change in the loaded load is suppressed.

According to the invention of claim 8, according to claim 1,
In addition to the operation of the invention according to any one of claims 7 to 7, when the brake operation member is operated by a brake, the wheel brake is driven by a braking force according to the brake operation force in addition to the braking by the brake means. Braking the vehicle through. Also, at the time of braking, the vehicle stops with the rotation of the drive wheels restricted.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) Hereinafter, a first embodiment in which the present invention is embodied in a driving force control device for a forklift will be described.
The embodiment will be described with reference to FIGS.

FIG. 1 is a schematic configuration diagram of a driving force control device provided in a forklift as an industrial vehicle. The output of the engine 10 is transmitted to the transmission 1 via a torque converter 11.
2 and the output of the transmission 12 is transmitted via a differential 13 to left and right front wheels 14 as drive wheels.

The engine 10 has a throttle opening T
A throttle actuator 15 for adjusting H is provided. The engine 10 has a magnetic sensor 1 for detecting the rotation speed of its crankshaft as the engine rotation speed Ne.
6 are provided.

In the torque converter 11, an input shaft 17 on the pump side is connected to an output shaft of the engine 10, and an output shaft 18 on the turbine side is connected to an input shaft of the transmission 12.
The transmission 12 is provided between an input shaft 19 connected to an output shaft 18 of the torque converter 11 and an output shaft 20 connected to the differential 13 side, with a reduction gear train for forward and reverse movement (not shown). And a forward clutch 21 and a reverse clutch 22 as brake means that are connected and operated by hydraulic pressure.

In the connected state, the forward clutch 21 connects the input shaft 19 and the output shaft 20 with a forward gear train. or,
In the connected state, the reverse clutch 22 connects the input shaft 19 and the output shaft 20 with a reverse gear train. Forward clutch 2
1 and the reverse clutch 22 are of a wet multi-plate type, and the clutch pressure P of the hydraulic oil supplied to each of the pressure receiving chambers 21a, 22a.
The connection is made in a connection state according to fcl and Prcl. The clutch pressures Pfcl, Prcl are both controlled from "0" to a predetermined maximum clutch pressure Pfcl100, Prcl100. And
When the clutch pressures Pfcl and Prcl are “0”, the clutches 21 and 22 are in a disconnected state in which the driving force from the engine 10 is not transmitted. When the clutch pressures Pfcl and Prcl are the maximum clutch pressures Pfcl100 and Prcl100, the engine 1 is not driven.
This is a completely connected state in which the driving force from 0 is transmitted without being restricted. Also, each of the clutches 21 and 22 has a clutch pressure P
fcl and Prcl are "0" from the maximum clutch pressure Pfcl100, P
In the state between rcl100, the state is a half-connected state in which the driving force from the engine 10 is transmitted while being limited according to the clutch pressures Pfcl and Prcl. In the housing of the transmission 12, an electromagnetic proportional pressure as a traveling electromagnetic pressure control valve and a braking electromagnetic pressure control valve for adjusting the clutch pressures Pfcl and Prcl of the pressure receiving chambers 21a and 22a for each of the clutches 21 and 22. Control valves (hereinafter, simply referred to as solenoid valves) 23 and 24 are provided.

As for the forward clutch 21 and the reverse clutch 22, the clutch which is not connected according to the traveling direction at that time is used as a hydraulic brake for braking the vehicle. Each of the clutches 21 and 22 is in the non-braking state when the clutch pressures Pfcl and Prcl as the brake pressures are "0" which is the non-braking brake pressure, and as the clutch pressures Pfcl and Prcl increase from "0". Thus, the vehicle can be braked with a large braking force.

Further, the transmission 12 is provided with a parking clutch brake 25 for restricting the movement of the vehicle during parking. The parking clutch brake 25 is a wet-type multi-plate clutch type. The brake pad 25a is pressed against the brake disc 25b by the urging force of an urging spring (not shown), and the brake clutch pressure of the hydraulic oil supplied to the pressure receiving chamber 25c. The pressure contact state of the brake pad 25a against the brake disk 25b is released by Pbcl. That is, the parking clutch brake 25 is in the maximum braking state when the brake clutch pressure Pbcl is "0", and the brake clutch pressure Pbcl becomes the maximum brake clutch pressure Pbcl100.
It becomes a non-braking state at the time of. The housing of the transmission 12 is provided with an electromagnetic proportional pressure control valve (hereinafter simply referred to as an electromagnetic valve) 26 for adjusting the brake clutch pressure Pbcl of the pressure receiving chamber 25c of the parking clutch brake 25.

Hydraulic oil is supplied to each of the solenoid valves 23, 24, and 26 from a hydraulic pump (not shown) provided in the housing of the transmission 12 and driven by the power of the engine 10.

The transmission 12 is provided with a magnetic sensor 28 for detecting the passage of a number of teeth corresponding to the torque converter output shaft rotation speed Nt of the gear 27 fixed to the input shaft 19.
The transmission 12 has a gear 29 fixed to the output shaft 20.
A magnetic sensor 30 is provided for detecting passage of a number of teeth corresponding to the transmission output shaft rotation speed Nd.

The driver's seat (not shown) is provided with an accelerator pedal 31 as a throttle operating member for changing the throttle opening TH of the engine 10. When the accelerator pedal 31 is not operated and the accelerator depression amount Acc as the throttle operation amount is “0”, the accelerator idle state Acc-idle
And a potentiometer 32 as a throttle operation detecting means for detecting the accelerator depression amount Acc when the accelerator is operated.

In the driver's seat, a brake pedal 33 is provided. The brake pedal 33 is provided with a brake switch 34 for detecting a brake state Brk in which the brake pedal 33 is operated.
Further, the brake pedal 33 is provided with an emulator 35 for generating a brake pressure Pbrk corresponding to the brake depression force. The emulator 35 is provided with a pressure sensor 36 for detecting the brake pressure Pbrk. In the present embodiment, the emulator 35 and the pressure sensor 36 constitute a brake operating force detecting unit.

The driver's seat is provided with a shift lever 37 as a direction switching operation member which is switched to switch each of the clutches 21 and 22 to the switching state or the completely connected state. The shift lever 37 has a shift position Ps as a switching position, a neutral position in which the clutches 21 and 22 are disengaged, a forward position switched from the neutral position in order to bring the forward clutch 21 into a completely connected state, and a reverse position. And a reverse position that is switched from a neutral position to bring the clutch 22 into a completely connected state. The shift lever 37 is provided with a shift position switch 38 as a direction detecting means for detecting the shift position Ps.

The driver's seat is provided with a mode switch 39 for presetting the deceleration during braking. The mode switch 39 has three deceleration setting positions Msel, ie, a normal position N, a hard position H, and a soft position S, as setting states for setting deceleration during braking.

The mast 40 provided at the front of the machine base includes a lift cylinder 41 operated by hydraulic oil supplied from a hydraulic pump, an inner mast 42 and a fork 43 which move up and down by the expansion and contraction of the lift cylinder 41. I have. The lift cylinder 41 includes a pressure sensor 44 as a load detection unit that detects an operating oil pressure corresponding to a load W of the load as a load loaded on the fork 43.
Is provided. A controller 45 for controlling the engine 10 and the clutch pressures Pfcl and Prcl of the clutches 21 and 22 is provided in the machine stand. The controller 45 has a magnetic sensor 16, 2 on its input side.
8, 30, potentiometer 32, brake switch 3
4, the pressure sensor 36, the shift position switch 38, the mode switch 39, and the pressure sensor 44 are electrically connected to each other, and the throttle actuator 15,
Each of the solenoid valves 23, 24, 26 is electrically connected.

Next, the electrical configuration of the traveling control device for a forklift constructed as described above will be described. FIG.
FIG. 2 is a block diagram illustrating an electrical configuration of a travel control device.

The magnetic sensor 16 outputs a pulse signal having a cycle proportional to the engine speed Ne of the engine 10 to the controller 45. The magnetic sensor 28 outputs a pulse signal having a cycle proportional to the torque converter output shaft rotation speed Nt of the torque converter 11 to the controller 45. The magnetic sensor 30 outputs to the controller 45 a pulse signal having a period proportional to the transmission output shaft rotation speed Nd and the vehicle speed V. The potentiometer 32 outputs to the controller 45 a signal corresponding to the accelerator idle state Acc-idle of the accelerator pedal 31 and a voltage signal proportional to the accelerator depression amount Acc. The brake switch 34 is connected to the brake pedal 3
A signal is output to the controller 45 when 3 is in the brake state Brk where the brake operation is performed. The pressure sensor 36 outputs a voltage signal proportional to the brake pressure Pbrk corresponding to the brake depression force to the controller 45. The shift position switch 38 outputs a signal corresponding to the shift position Ps of the shift lever 37 to the controller 45. The mode switch 39 outputs a signal corresponding to each deceleration setting position Msel to the controller 45. The pressure sensor 44 outputs a voltage signal corresponding to the load W of the load to the controller 45.

The controller 45 includes an A / D converter 51,
52, 53, a microcomputer (hereinafter simply referred to as a microcomputer) 54 as a rotational acceleration detecting means, a drive circuit 55, and the like.

In the present embodiment, the gear 29, the magnetic sensor 30, and the microcomputer 54 constitute driving wheel rotational speed detecting means, and the mode switch 39 and the microcomputer 54 constitute deceleration setting means. The microcomputer 54 and the drive circuit 55
Constitute the clutch control means and the brake control means.

The microcomputer 54 has a central processing unit (hereinafter referred to as C).
PU) 56, a read-only memory (ROM) 57, a readable / rewritable memory (RAM) 58, a timer 59, an input interface 60, an output interface 61, and the like.

The CPU 56 has an output interface 61
, A control signal for causing the throttle actuator 15 to have a predetermined throttle opening TH is output to the drive circuit 55. Based on this control signal, the drive circuit 55 sets the throttle opening TH of the throttle actuator 15 within a predetermined range. adjust. The CPU 56 sends a control signal for commanding the clutch pressure Pfcl supplied by the solenoid valve 23 to the drive circuit 5.
5, and the drive circuit 55 adjusts the clutch pressure Pfcl supplied from the solenoid valve 23 in the range from “0” to the maximum clutch pressure Pfcl100 based on the control signal. The CPU 56 outputs a control signal for instructing the clutch pressure Prcl supplied by the solenoid valve 24 to the drive circuit 55. Based on this control signal, the drive circuit 55 causes the clutch pressure Prc supplied by the solenoid valve 24 to change.
l is adjusted in the range from "0" to the maximum clutch pressure Prcl100. Further, the CPU 56 outputs a control signal for instructing the brake clutch pressure Pbcl supplied by the solenoid valve 26 to the drive circuit 55. Based on this control signal, the drive circuit 55 determines the brake clutch pressure Pbcl supplied by the solenoid valve 26. "0"
From the maximum brake clutch pressure Pbcl100.

The ROM 57 stores control programs for a throttle control process, a clutch control process, a parking brake control process, and a brake control process executed by the CPU 56. The ROM 57 stores an arithmetic expression TH = k · Acc (k is a constant) used in the throttle control process, and initial clutch pressures Pfcl 0 and Prcl used in the clutch control process.
0 and an allowable determination value ΔN0 of the torque converter input shaft rotation speed Np (that is, the engine speed Ne) and the torque converter output shaft rotation speed Nt. ROM5
7 is a stop vehicle speed V0 used in the parking brake control process.
And the standby time T0. Furthermore, ROM5
7 stores maps M1 and M2 used in the braking control process, a low-speed braking determination value V1, a rotational acceleration determination value α0, and a rotational acceleration reference value αmode.

(1) Throttle control processing The CPU 56 executes the ROM 57 as throttle control processing.
The throttle opening TH corresponding to the accelerator depression amount Acc is obtained by using the arithmetic expression TH = k · Acc stored in the equation (3), and the throttle actuator 15 is controlled to the throttle opening TH.

(2) Clutch control process As a clutch control process, the CPU 56 determines the shift position Ps at that time from the shift position signal, and when the shift position Ps is in the neutral position, controls the solenoid valves 24 and 25 to move forward. The clutch pressures Pfcl and Prcl of the first and second clutches 21 and 22 are set to “0”.

The CPU 56 performs a clutch control process as follows:
When the shift position Ps switches from the neutral position to the forward position, the solenoid valve 23 is controlled to reduce the clutch pressure Pfcl of the forward clutch 21 from “0” to a predetermined initial clutch pressure Pfcl 0.
And

When the clutch pressure Pfcl of the forward clutch 21 is rapidly increased from "0" to "0" in the stopped state of the vehicle when the vehicle is stopped, the initial clutch pressure Pfcl 0 is changed via the forward clutch 21. The clutch pressure P at which the vehicle starts to slightly move by the driving force transmitted to the front wheels 14
fcl, which is the clutch pressure Pfcl at which the acceleration applied to the vehicle body does not suddenly change.

The CPU 56 performs a clutch control process as follows:
After the clutch pressure Pfcl of the forward clutch 21 is changed from “0” to a predetermined initial clutch pressure Pfcl 0, the clutch pressure Pfc
is maintained at the initial clutch pressure Pfcl 0.

Next, the CPU 56 determines, from the engine speed Ne and the torque converter output shaft rotation speed Nt, that the rotation speed difference ΔN has become less than a predetermined allowable determination value ΔN0 as a starting clutch control process. To detect. Then, the CPU 56 determines that the rotational speed difference ΔN is equal to the allowable determination value ΔN0.
From the point where it becomes less than the initial clutch pressure Pfcl
The clutch pressure Pfcl maintained at 0
fcl100.

Similarly, as a clutch control process, when the shift position Ps is switched from the neutral position to the reverse position, the CPU 56 controls the solenoid valve 24 to change the clutch pressure Prcl 0 from “0” to the initial clutch pressure Prcl 0. After that, the initial clutch pressure Prcl is maintained at 0. And the CPU 56
Is the engine speed Ne and the torque converter output shaft rotation speed Nt
When the rotational speed difference ΔN becomes smaller than the allowable determination value ΔN0, the clutch pressure Prcl is changed from the initial clutch pressure Prcl0 to the maximum clutch pressure Prcl100.

(3) Parking Brake Control Processing As a parking brake control processing, the CPU 56 determines from the signal output from the shift position switch 38 that the shift position Ps of the shift lever 37 has been switched from the neutral position to the forward position or the reverse position. When the accelerator is not in the idle state Acc-idle, the solenoid valve 26 is controlled to control the brake clutch pressure P of the parking clutch brake 25.
The parking clutch brake 25 is changed from the brake operation state to the brake release state by setting bcl from “0” to the maximum brake clutch pressure Pbcl100.

The CPU 56 calculates the vehicle speed V from the transmission output shaft rotation speed Nd as a parking brake control process, and sets the calculated vehicle speed V in advance to determine whether or not the vehicle is stopped. If the stop vehicle speed V0 is lower than the set stop vehicle speed V0 and the duration of the brake state Brk measured by the timer 59 exceeds a preset standby time T0, it is determined that the vehicle is in a stop state. And C
The PU 56 controls the solenoid valve 26 to change the brake clutch pressure Pbcl from the maximum brake clutch pressure Pbcl100 to “0”.
As a result, the parking clutch brake 25 is changed from the brake release state to the brake operation state.

(4) Braking control processing As the braking control processing, the CPU 56 starts from the shift position Ps and sets the clutches 21 and 22 of the two clutches 21 and 22 that are not connected, for example, the shift position Ps to the forward position. Sometimes the reverse clutch 22 is determined. And
When the CPU 56 determines that the brake state is Brk based on the brake signal input from the brake switch 34,
Based on the signal input from the pressure sensor 36, the map M1
Then, a reference clutch pressure Prcl (Pbrk) of the reverse clutch 22 corresponding to the brake pressure Pbcl at that time is obtained.
The map M1 has a reference clutch pressure Prc, as shown in FIG.
l (Pbrk) is set in a relation proportional to the brake pressure Pbcl. That is, the CPU 56 applies a clutch pressure P of a magnitude corresponding to the brake depressing force to the reverse clutch 22.
Supply rcl.

The CPU 56 performs a braking control process as follows:
The reference clutch pressure Prcl (Pbrk) of the reverse clutch 22 determined with respect to the brake pressure Pbrk at that time is added to the load correction coefficient determined by using the map M2 from the load W of the load detected from the signal input from the pressure sensor 44. The value multiplied by kw is defined as an initial brake clutch pressure Prcl 0 (Pbrk, W) that is actually supplied to the reverse clutch 22. As shown in FIG. 4, the map M2 sets the load correction coefficient kw in a relation proportional to the clutch pressure Prcl. That is, CP
U56 is an initial brake clutch pressure Prc that increases as the load W of the load increases for the same brake depression force.
10 (Pbrk, W).

The CPU 56 performs a braking control process as follows.
From the transmission output shaft rotation speed Nd, the rotational acceleration α of the front wheels 14 is calculated.
(<0) are sequentially calculated. The CPU 56 performs the braking control process when the calculated rotational acceleration α is smaller than a preset rotational acceleration determination value α0 (<0), that is, when the magnitude of the rotational acceleration α is larger than the rotational acceleration determination value α0. When it becomes larger than the above, the clutch pressure Prcl of the reverse clutch 22 not selected by the shift lever 37
From the initial brake clutch pressure Prcl 0 (Pbrk, W) to “0” which is the non-braking brake pressure. Also, the CPU 56
Is, when the rotation acceleration α becomes less than the rotation acceleration determination value α0 and then becomes the rotation acceleration determination value α0 or more again,
The clutch pressure Prcl of the reverse clutch 22 is changed from “0” to a brake clutch pressure Prcl (Pbrk, W) smaller than the initial brake clutch pressure Prcl 0 (Pbrk, W). In the present embodiment, the rotational acceleration determination value α0
Is set to determine the locked state of the front wheel 14 (slip rate 100%) during braking during traveling.

FIG. 5 is a time chart showing changes in the brake pressure Pbrk, the rotational acceleration α of the front wheels 14, and the clutch pressure Prcl of the reverse clutch 22 during braking in the forward running state. The CPU 56, as shown in FIG.
When the brake pedal 33 is depressed, the clutch pressure Prcl of the reverse clutch 22 is set from “0” to an initial brake clutch pressure Prcl 0 (Pbrk, W) which is set according to the brake pressure Pbrk and the load W of the load. And
As a result, the reverse clutch 22 changes from the disconnected state to the semi-connected state, and the front wheel 14 is braked by the reverse driving force transmitted from the engine 10 by the reverse clutch 22,
The rotation acceleration α decreases, that is, the magnitude of the rotation acceleration α increases. When the rotational acceleration α becomes smaller than the rotational acceleration determination value α0 at the time point a, the CPU 56 determines that the clutch pressure Prcl
From the initial brake clutch pressure Prcl0 (Pbrk, W) to “0”. As a result, the reverse clutch 22 changes from the semi-connected state to the disconnected state, the front wheel 14 is no longer braked, and the rotational acceleration α increases again. When the increasing rotational acceleration α becomes the rotational acceleration determination value α0 or more again at the time point b,
The CPU 56 calculates the clutch pressure Prcl of the reverse
From "0", the initial brake clutch pressure Prcl 0 (Pbrk
, W), the brake clutch pressure Prcl (Pbrk
, W).

The CPU 56 performs a braking control process as follows:
The deceleration setting position Msel set by the mode switch 39
Then, a rotation acceleration reference value αmode corresponding to the deceleration setting position Msel is set. That is, the CPU 56 sets a smaller rotation acceleration reference value αmode closer to the rotation acceleration determination value α0 than the rotation acceleration reference value αmode set when the deceleration setting position Msel is the normal position N when the hardware position H is set. Conversely, when the position is the soft position S, a large rotational acceleration reference value αmode farther from the rotational acceleration determination value α0 is set. Then, the CPU 56 determines that when the rotational acceleration α becomes less than the rotational acceleration determination value α0 and then becomes greater than or equal to the rotational acceleration determination value α0 again during braking,
Deviation Δα of rotation acceleration α from rotation acceleration reference value αmode when rotation acceleration reference value αmode is smaller than set rotation acceleration reference value αmode
(= Αmode−α;> 0), the initial brake clutch pressure Prcl 0 (Pbrk, W) by an amount corresponding to the added value ΣΔα.
Brake clutch pressure Prcl (Pbrk,
W) is replaced with “0” and is set as a new clutch pressure Prcl of the reverse clutch 22.

When the clutch pressure Prcl of the reverse clutch 22 is set to the brake clutch pressure Prcl (Pbrk, W), the CPU 56 performs a braking control process every time the rotational acceleration α becomes smaller than the rotational acceleration determination value α0. , The clutch pressure Prcl is changed to the brake clutch pressure Prcl
(Pbrk, W) is set to “0”. Also, the CPU 56
As the braking control process, when the clutch pressure Prcl is set to “0” and the rotational acceleration α is equal to or greater than the rotational acceleration determination value α0, the sum of the rotational acceleration α and the deviation Δα from the rotational acceleration reference value αmode ΣΔα The initial brake clutch pressure Prcl 0 (Pbrk,
New brake clutch pressure Prcl smaller than W)
(Pbrk, W) is replaced with “0” and a new clutch pressure P
rcl.

As shown in FIG. 5, after the rotational acceleration α has become less than the rotational acceleration determination value α0, when the rotational acceleration α again becomes greater than or equal to the rotational acceleration determination value α0 at the time point b, the CPU 56 sets the rotational acceleration reference value. The initial brake clutch has a size corresponding to the added value ΣΔα of the deviation Δα of the rotation acceleration α from the rotation acceleration reference value αmode when the rotation acceleration α is less than the value αmode, that is, the size corresponding to the area of the vertical line region indicated by A. Pressure P
The brake clutch pressure Prcl (Pbrk, W) reduced from rcl 0 (Pbrk, W) is set as a new clutch pressure Prcl.

Then, as shown in FIG.
Changes the clutch pressure Prcl to the brake clutch pressure Prcl (P
brk, W), each time the rotational acceleration α becomes less than the rotational acceleration determination value α0 (time point c), the clutch pressure P
rcl is the brake clutch pressure Prcl (Pbrk,
W) to “0”. Further, when the clutch acceleration Prcl is set to “0” and the rotational acceleration α becomes equal to or greater than the rotational acceleration determination value α0 (at time d), the deviation of the rotational acceleration α up to that point from the rotational acceleration reference value αmode is determined. A new brake clutch pressure Prcl (Pbrk, W), which is smaller than the initial brake clutch pressure Prcl 0 (Pbrk, W) by an amount corresponding to the added value ΣΔα of Δα,
A new clutch pressure Prcl is set instead of “0”.

Further, in the braking control process, when the vehicle speed V is equal to or less than the predetermined low-speed braking determination value V1, the rotation acceleration α is reduced to the rotation acceleration determination value α.
Even if it is less than 0, the rotational acceleration α is the rotational acceleration determination value α
The clutch pressure Prcl is controlled in the same manner as when it is 0 or more. That is, when the vehicle speed V becomes equal to or less than the low-speed braking determination value V1 due to the braking, the CPU 56 determines that the reverse clutch 2
The clutch pressure Prcl of No. 2 is not set to “0”. And CP
U56 is the same as when the rotational acceleration α is equal to or greater than the rotational acceleration determination value α0.
The rotational acceleration reference value αmo of the rotational acceleration α when it is less than
The brake clutch pressure Prcl (Pbrk, Pbrk, Wc) is smaller than the initial brake clutch pressure Prcl 0 (Pbrl, W) by an amount corresponding to the added value ΣΔα of the deviation Δα from de.
W) is the clutch pressure Prcl. Low speed braking judgment value V1
For example, when control is performed to switch the clutch pressure Prcl to “0” and the brake clutch pressure Prcl (Pbrk, W) based on the fact that the rotational acceleration α has become less than the rotational acceleration reference value αmode during braking, This is the upper limit of the vehicle speed V at which the vehicle immediately before stopping may be jerky.

As shown in FIG. 5, the CPU 56
Is lower than the low-speed braking determination value V1 and thereafter, even if the rotational acceleration α is less than the rotational acceleration reference value αmode, the clutch pressure Prcl is changed to the brake clutch pressure Prcl (P
brk, W), without adding “0” to the sum Δ 偏差 α of the deviation Δα
Initial brake clutch pressure Prcl0 by the size corresponding to
A new brake clutch pressure Prcl (Pbrk, W) smaller than (Pbrl, W) is defined as a clutch pressure Prcl.

The CPU 56 performs a braking control process as follows:
When the shift position Ps is the reverse position, the clutch pressure Pfcl of the forward clutch 21 is increased, and when the shift position Ps is the forward position, the clutch pressure Prcl of the reverse clutch 22 is increased.
Is controlled in the same manner as

Next, the operation of the traveling control device for a forklift constructed as described above will be described. After the engine 10 is started, when the shift lever 37 is switched from the neutral position to the forward position and the accelerator pedal 31 is depressed, the CPU 56 executes the parking brake control process, thereby causing the clutch pressure of the parking clutch brake 25 to be increased. By controlling Pbcl, the parking clutch brake 25 is changed from the braking state to the non-braking state. Also, CPU
56 executes the clutch control process to change the forward clutch 21 from the disengaged state to the completely connected state while keeping the reverse clutch 22 in the disengaged state. Further, the CPU 56 sets the throttle opening TH of the throttle actuator 15 to the throttle opening TH corresponding to the accelerator depression amount Acc of the accelerator pedal 31 by executing the throttle control control processing.

The CPU 56 operates for a predetermined time (for example, 10 mm
sec. The braking control process executed every time the vehicle is braked by controlling the connection state of the reverse clutch 22 at the time of braking in the forward state. Hereinafter, when the vehicle advances, the CPU 56
Will be described with reference to the flowchart shown in FIG.

In the braking control process, the CPU 56 first determines in step (hereinafter simply abbreviated as S) 10 whether or not the brake pedal 33 is in a state in which the brake pedal 33 is depressed by the brake state Brk. CPU5
6, when it is determined that the brake operation is performed in S10, the rotational acceleration α between the previous process and the current process is calculated from the transmission output shaft rotation speed Nd detected every time this process is performed. .

Next, in S30, the CPU 56 calculates a deviation Δα of the rotational acceleration α exceeding the rotational acceleration reference value αmode set at that time from the rotational acceleration reference value αmode. In S40, the CPU 56 numerically limits the deviation Δα to a range from “0” to a predetermined value α1. And CPU
In step S50, a deviation addition value αintg obtained by adding the deviation Δα obtained for each process is calculated.

Next, in S60, the CPU 56 determines whether or not the rotational acceleration α obtained in the current processing is less than the rotational acceleration determination value α0 and whether the vehicle speed V exceeds the low-speed vehicle speed determination value V1. .

In S60, the CPU 56 determines whether the rotational acceleration α is equal to or greater than the rotational acceleration determination value α0 or the vehicle speed V
Is less than or equal to the low-speed vehicle speed determination value V1 at S70.
The initial brake clutch pressure Prcl is calculated based on the brake pressure Pbk corresponding to the brake depressing force and the load W of the load.
0 (Pbrk, W) is obtained. Next, the CPU 56 proceeds to S8
With 0, the deviation addition value αintg is normalized.

Next, in S90, the CPU 56 changes the clutch pressure Prcl to the initial brake clutch pressure Prcl 0 (Pbrk
, W), the process is terminated with a size closer to “0” by a size corresponding to the normalized deviation addition value [αintg].

On the other hand, if the rotational acceleration α is less than the rotational acceleration determination value α0 and the vehicle speed V exceeds the low speed vehicle speed determination value V1 in S60, the CPU 56 sets the clutch pressure Prcl to “0” in S100. , And the present process ends.

If the CPU 56 determines in step S10 that the brake pedal 33 is not in the state in which the brake pedal is depressed because the brake state is not the brake state Brk, the process proceeds to step S1.
In step 10, the deviation addition value αintg obtained up to the previous processing is initialized to “0”, and then this processing ends.

Therefore, when the brake pedal 33 is depressed, the controller 45 controls the two clutches 2.
By controlling the clutch on the side opposite to the advancing side from the disengaged state to the semi-connected state, the vehicle is braked with a braking force having a magnitude corresponding to the depressing operation force. While the left and right front wheels 14 are locked and slip on the road surface, the braking side clutch 22 (2
1) is controlled to stop the braking.

When the vehicle speed V becomes equal to or less than the low speed braking determination value V1 due to braking, braking is not performed even if the left and right front wheels 14 are locked and slip on the road surface.
When the brake pedal 33 is depressed while the shift position Ps is switched to the reverse position and the vehicle is traveling backward, the CPU 56 controls the clutch of the forward clutch 21 by the same braking control process. Pressure P
Control fcl.

The vehicle speed V of the vehicle is reduced by the braking to the stop vehicle speed V0.
Is less than the standby time T
When the brake pedal is depressed beyond 0, the CPU 56
Controls the clutch pressure Pbcl of the parking clutch brake 25 by executing the parking brake control processing, and changes the parking clutch brake 25 from the non-braking state to the braking state. As a result, when the vehicle stops, the parking clutch brake 25 is automatically set.

Therefore, according to the present embodiment described in detail above, there are the following operations and effects. (1) When the brake pedal 33 is depressed during traveling, one of the forward and reverse clutches 21 and 22 provided on the transmission 12 that is not selected by the shift lever 37, that is, reverses during forward travel. From the clutch pressure Prcl of the non-braking state “0” which is the clutch pressure Prcl in the non-braking state, the clutch pressure Prcl (Pbrk, W) for generating a predetermined braking force is set. As a result, the vehicle is braked by the reverse clutch 22 which is changed from the disconnected state to the semi-connected state. Further, when the rotational acceleration α calculated from the rotational speed of the front wheels 14 becomes smaller than the preset rotational acceleration determination value α0, it is determined that the front wheels 14 are locked by braking by the reverse clutch 22. The clutch pressure Prcl of the reverse clutch 22
From the brake clutch pressure Prcl (Pbrk, W) to "0" which is the non-braking brake pressure. As a result, the rotation of the front wheel 14 is permitted by the reverse clutch 22 that has been changed from the semi-connected state to the disconnected state. Therefore, both clutches 2
The vehicle is braked by the clutch 22 (21) which is not selected during traveling, and the braking force by the clutch 22 (21) is limited when the front wheel 14 slips on the road surface due to the braking. Thus, slip of the front wheel 14 is suppressed.

As a result, the operation of the clutch pedal is not required, and the switching operation of the shift lever 37 allows the clutch 21, 21 to be operated.
In addition to being able to automatically perform the connection / disconnection operation at 22, the slippage of the front wheels 14 on the road surface during braking can be suppressed without increasing the number of new components.

(2) Of the forward clutch 21 and the reverse clutch 22 provided in the transmission 12, the clutch 22 not selected by the shift lever 37 during traveling.
The brake is applied by (21). Therefore, the present invention can be applied to a vehicle without the parking clutch brake 25.

(3) When the vehicle speed V is equal to or less than the low-speed braking determination value V1 and the change in the braking force by the forward clutch 21 or the reverse clutch 22 causes a large change in the acceleration applied to the vehicle, the rotational acceleration Even if α is less than the rotational acceleration determination value α0, the rotational acceleration determination value α0
As in the above case, the clutch pressure of the forward clutch 21 or the reverse clutch 22 is controlled.
Therefore, when the vehicle is about to stop, the braking force by the forward clutch 21 or the reverse clutch 22 is not limited, and the vehicle stops smoothly without jerking.

(4) When the front wheel 14 is locked during braking and the rotational acceleration α becomes smaller than the rotational acceleration determination value α0, the clutch pressure Prcl of the reverse clutch 22 on the braking side is changed to the initial brake clutch pressure Prcl 0 ( Pbrk,
W) is changed to "0" to release the braking. When the front wheel 14 comes out of the locked state due to the release of the braking and the rotational acceleration α again becomes the rotational acceleration determination value α0 or more, the rotational acceleration α is smaller than the rotational acceleration reference value αmode. The brake clutch pressure Prcl (Pbrk, W), which is smaller than the initial brake clutch pressure Prcl 0 (Pbrk, W) by an amount corresponding to the deviation addition value ΣΔα of the deviation Δα, is set to a new clutch pressure P
rcl. Therefore, when the front wheel 14 is locked during braking, the braking is released, and when the front wheel 14 comes out of the locked state due to the release of the braking,
The longer the locked state of the front wheel 14 when the braking is released, the smaller the braking force is applied to the braking.

Accordingly, the braking force of the clutch 22 (21) is controlled so that the braking is performed while the sliding degree is reduced according to the sliding degree of the front wheel 14 during braking. As a result, the vehicle can be braked while the front wheels 14 are prevented from slipping.

(5) The rotational acceleration reference value αmode is changed by changing the setting of the deceleration setting position Msel with the mode switch 39. Therefore, if the rotational acceleration reference value αmode is set to a value larger than the rotational acceleration determination value α0 by the deceleration setting position Msel, the deviation addition value ΣΔα used during braking increases.
Then, the braking force when the rotational acceleration α becomes equal to or greater than the rotational acceleration determination value α0 is further reduced.

Accordingly, the braking force of the clutch 22 (21) is controlled so that the degree of slippage of the front wheel 14 during braking is adjusted according to the deceleration setting position Msel. Can be adjusted. For this reason, for example, when the load is easily collapsed, the deceleration with respect to the amount of depression of the brake pedal 33 is reduced by setting the rotation acceleration reference value αmode to a larger value that is farther from the rotation acceleration determination value α0, and the vehicle does not suddenly decelerate. You can do so.

(6) The load W of the load is detected, and during braking, the greater the load W, the greater the braking force applied to the braking side clutch 22 (21). Accordingly, a change in the deceleration of the vehicle with respect to the depression force of the brake pedal 33 with respect to a change in the load W of the load is suppressed. As a result, even when carrying a load whose load W is unknown, the vehicle can be stopped at the traveling distance predicted by the driver.

(Second Embodiment) Next, the present invention will be described with reference to the first embodiment.
A second embodiment embodied in a travel control device of a forklift will be described with reference to FIGS. In this embodiment, the wheel brakes 4 which are hydraulically actuated by the depression of the brake pedal 33 are applied to the left and right front wheels 14 in the first embodiment.
6 is different from that of the first embodiment only in that the parking clutch brake 25 and the wheel brake 46 cooperate to perform the braking of the vehicle based on the brake depression operation of the brake pedal 33. . Therefore, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. Only the wheel brake 46 and the braking control process executed by the microcomputer 54 will be described in detail.

FIG. 7 is a schematic configuration diagram of the traveling control device. Each of the left and right front wheels 14 has a wheel brake 46
Is provided. Each of the wheel brakes 46 is a hydraulic brake, and is operated by hydraulic oil supplied from a master cylinder (not shown) operated by depressing the brake pedal 33. The master cylinder supplies operating oil pressure to the wheel brake 46 in accordance with the depression force of the brake pedal 33. The wheel brake 46 applies a braking force corresponding to the supplied hydraulic pressure to the front wheels 14.
Brake.

The parking clutch brake 25 as a braking means has a capacity capable of braking the vehicle during traveling in cooperation with the wheel brake 46 in addition to a capacity capable of braking the vehicle during parking. . In the present embodiment, the electromagnetic proportional pressure control valve 26 is a braking electromagnetic pressure control valve, and the brake clutch pressure Pbcl as the brake pressure supplied to the parking clutch brake 25 is the non-braking brake pressure during non-braking. The adjustment is performed in a range from the maximum brake clutch pressure Pbcl100 to the brake pressure “0” at the time of maximum braking.

The microcomputer 54 executes a braking control process described in detail below instead of the braking control process in the first embodiment. (4) Braking control processing When the CPU 56 determines that the brake state has been changed to the braking state Brk from the brake signal input from the brake switch 34 as the braking control processing, the CPU 56 determines the current braking state from the map M3 based on the pressure signal input from the pressure sensor 36. Pressure P
A reference clutch pressure Pbcl (Pbrk) to be supplied to the parking clutch brake 25 is determined in accordance with brk. Map M3
Sets the reference clutch pressure Pbcl (Pbrk) in a relation proportional to the brake pressure Pbrk, similarly to the map M1 of the first embodiment. That is, the CPU 56 supplies the reverse clutch 22 with the reference clutch pressure Pbcl (Pbrk) having a magnitude corresponding to the brake depression force.

The CPU 56 performs a braking control process as follows.
The reference clutch pressure Pbcl (Pbrk) of the parking clutch brake 25 required for the brake pressure Pbrk at that time.
) Is multiplied by the load correction coefficient kw obtained by using the map M2 from the load W of the load detected from the pressure signal input from the pressure sensor 44, and the initial brake clutch pressure Pbcl actually supplied to the parking clutch brake 25. 0 (P
brk, Wk). That is, the CPU 56 supplies an initial brake clutch pressure Pbcl 0 (Pbrk, W) which is larger as the load W of the load is larger for the same brake depression force.

Further, the CPU 56 performs a braking control process as follows.
From the transmission output shaft rotation speed Nd, the rotational acceleration α of the front wheels 14 is calculated.
Are sequentially calculated. The CPU 56 performs, as a braking control process,
When the calculated rotational acceleration α becomes smaller than the preset rotational acceleration determination value α0, the brake clutch pressure Pbcl supplied to the parking clutch brake 25 is increased from the initial brake clutch pressure Pbcl 0 (Pbrk, W). It is "0" which is the non-braking brake pressure. Further, when the rotational acceleration α becomes less than the rotational acceleration determination value α and then becomes the rotational acceleration determination value α0 or more again, the CPU 56 changes the brake clutch pressure Pbcl to the initial brake clutch pressure Pbcl 0.
(Pbrk, W) Brake clutch pressure Pbcl smaller than
(Pbrk, W).

Further, the CPU 56 executes a deceleration setting position M set by the mode switch 39 as a braking control process.
From sel, a rotational acceleration reference value αmode corresponding to the deceleration setting position Msel is set. Then, the CPU 56
When the magnitude of the rotational acceleration α becomes less than the rotational acceleration determination value α0 and then becomes the rotational acceleration determination value α0 or more again, the rotational acceleration of the rotational acceleration α when the rotational acceleration α is less than the set rotational acceleration reference value αmode The brake clutch pressure Pbcl (Pbrk, W) reduced from the initial brake clutch pressure Pbcl 0 (Pbrk, W) by an amount corresponding to the addition value ΣΔα of the deviation Δα from the reference value αmode is replaced with a new brake clutch pressure Pbcl. I do.

When the brake clutch pressure Pbcl of the parking clutch brake 25 is set to the brake clutch pressure Pbcl (Pbrk, W) as the braking control process, the CPU 56 determines that the magnitude of the rotational acceleration α is equal to the rotational acceleration determination value α0. Each time it becomes less than the brake clutch pressure P
bcl is the current brake clutch pressure Pbcl (Pbrk,
W) to “0”. When the rotational acceleration α is equal to or greater than the rotational acceleration determination value α0 while the brake clutch pressure Pbcl is “0”, the CPU 56 changes the brake clutch pressure Pbcl from “0” to the rotational acceleration α until that time. A new brake clutch pressure Pbcl (Pbrk, W) reduced from the previous brake clutch pressure Pbcl (Pbrk, W) by an amount corresponding to the added value ΣΔα of the deviation Δα with respect to the acceleration reference value αmode.

Next, the operation of the traveling control device for a forklift constructed as described above will be described. When the brake pedal 33 is depressed while the vehicle is traveling forward, each wheel brake 46 is moved from the master cylinder.
Is supplied with hydraulic oil. As a result, the vehicle is braked by each wheel brake 46 with a braking force of a magnitude corresponding to the depression force of the brake pedal 33.

On the other hand, when the CPU 56 determines that the brake state Brk has been reached in the braking control processing executed every predetermined time, the CPU 56 changes the brake clutch pressure Pbcl of the parking clutch brake 25 to the maximum brake clutch pressure Pbcl1.
From 00, an initial brake clutch pressure Pbcl 0 (Pbrk, W) set according to the brake pressure Pbrk and the load W of the load.
And As a result, the parking clutch brake 25 is changed from the disconnected state to the semi-connected state, and the rotation of the front wheel 14 is also braked by the parking clutch brake 25 in addition to the wheel brake 46, so that the vehicle is braked.

When braking is applied to the rotation of the front wheel 14, the rotation speed decreases and the rotational acceleration α decreases. When the rotational acceleration α becomes smaller than the rotational acceleration determination value α0, the CPU 56
Calculates the brake clutch pressure Pbcl of the parking clutch brake 25 as the initial brake clutch pressure Pbcl 0 (Pbrk,
W) to the maximum brake clutch pressure Pbcl100. As a result, the parking clutch brake 25 changes from the semi-connected state to the disconnected state, and the braking on the front wheels 14 is released.

When the braking of the front wheels 14 is released, the rotation speed increases and the rotation acceleration α increases. Rotational acceleration α
Is greater than or equal to the rotation acceleration determination value α0, the CPU 56
Brake clutch pressure Pbc of parking clutch brake 25
l is the deviation Δ from the maximum brake clutch pressure Pbcl when the rotational acceleration α is less than the rotational acceleration reference value αmode.
The brake clutch pressure Pbcl (Pbrk, W) is increased from the initial brake clutch pressure Pbcl 0 (Pbrk, W) by an amount corresponding to the added value ΣΔα of α. as a result,
The parking clutch brake 25 changes from the disconnected state to the semi-connected state again, the rotation of the front wheels 14 is braked, and the vehicle is braked. At this time, the brake clutch pressure Pbcl of the parking clutch brake 25 becomes the initial brake clutch pressure Pbc.
l Brake clutch pressure Pbc higher than 0 (Pbrk, W)
Since l (Pbrk, W), the braking force is suppressed as compared with the first braking state.

When the rotation of the front wheel 14 is braked again, the rotation speed decreases and the rotation acceleration α decreases. When the rotational acceleration α again becomes smaller than the rotational acceleration determination value α0, the CPU
Reference numeral 56 denotes the brake clutch pressure Pbcl of the parking clutch brake 25, and the brake clutch pressure Pbcl (Pbrk,
W) to the maximum brake clutch pressure Pbcl100. As a result, the parking clutch brake 25 changes from the semi-connected state to the disconnected state, and the braking on the front wheels 14 is released.

When the braking on the front wheels 14 is released again, the rotation speed increases again and the rotation acceleration α increases. When the rotational acceleration α becomes equal to or greater than the rotational acceleration determination value α0, the CPU 56 changes the brake clutch pressure Pbcl of the parking clutch brake 25 to the maximum brake clutch pressure Pbc.
From l100, the initial brake clutch pressure Pbcl 0 (Pbrk, W) is increased by an amount corresponding to the added value ΣΔα of the deviation Δα when the rotational acceleration α is less than the rotational acceleration determination value α0.
Brake clutch pressure Pbcl (Pbrk, W)
And As a result, the parking clutch brake 25 is changed from the disconnected state to the semi-connected state again, and the rotation of the front wheels 14 is braked to apply braking to the vehicle. At this time, the brake clutch pressure Pbcl (Pbrk, W) of the parking clutch brake 25 is set to be larger than the initial brake clutch pressure Pbcl 0 (Pbrk, W) by a predetermined amount, so that the first time. The braking force is further suppressed as compared to the braking state.

Thereafter, while the brake pedal 33 is operated by depressing the brake and the brake state is Brk, C
The PU 56 applies the brake clutch pressure Pbcl of the parking clutch brake 25 every time the front wheel 14 is braked by the parking brake clutch 25 and the rotational acceleration α becomes less than the rotational acceleration determination value α0. From the pressure Pbcl (Pbrk, W), the maximum brake clutch pressure Pbcl100 is set. When the rotational acceleration α again becomes equal to or greater than the rotational acceleration determination value α0, the CPU 56 determines the initial brake clutch pressure by an amount corresponding to the added value ΣΔα of the deviation Δα of the rotational acceleration α from the rotational acceleration determination value α0 up to that time. The brake clutch pressure Pbcl (Pbrk, W) increased from Pbcl 0 (Pbrk, W) is set as a new brake clutch pressure Pbcl. Then, the vehicle is decelerated by the braking, and the rotational acceleration α at the time of braking becomes the rotational acceleration determination value α.
When it does not become less than 0, the brake clutch pressure Pbcl of the parking clutch brake 25 is maintained at the brake clutch pressure Pbcl (Pbrk, W) at the time of the last braking until the brake pedal 33 is no longer depressed. As a result, even when the vehicle is stopped, braking by the parking clutch brake 25 is maintained in addition to braking by the wheel brake 46.

As a result, at the time of braking during traveling, the brake pedal 33 is depressed by the brake pedal to operate the wheel brake 46 to apply a braking force corresponding to the brake depressing force to the front wheels 14, and at the same time, the parking clutch brake 25 operates to apply a braking force to the front wheels 14 according to the brake depressing force, the load W of the load, and the deceleration setting position of the mode switch 39. That is, when the brake pedal 33 is depressed during running, as shown in FIG. 9, the braking force is composed of the braking force of the wheel brake 46 and the braking force of the parking clutch brake 25, and the brake pressure Pbrk
Generates a braking force Fb proportional to. And the braking force Fb
The front wheel 14 is not locked in the locked state because the braking force by the parking clutch brake 25 is controlled.

When the brake pedal 33 is depressed while the vehicle is traveling backward, the clutch pressure Pbcl of the parking clutch brake 25 is controlled in the same manner as when the vehicle is traveling forward. Then, the vehicle is braked by the wheel brake 46 and the parking clutch brake 25.

Therefore, according to the present embodiment described in detail above, (1), (4) to (4) in the first embodiment are used.
In addition to the functions and effects described in (6), there are the following functions and effects.

(7) The braking from running is performed by the parking clutch brake 25 used during parking.
Therefore, the reverse clutch 22 does not wear on the forward clutch 21 earlier due to frequent braking during forward travel as compared with the case of braking by the forward and reverse clutches 21 and 22.

(8) The braking from running is cooperatively performed by the parking clutch brake 25 and the wheel brake 46. Accordingly, early wear of the parking clutch brake 25 due to braking during traveling can be suppressed, and the maintenance and inspection time in the transmission 12 can be extended.

(9) When the vehicle is stopped by braking, in addition to braking by the parking clutch brake 25, the rotation of the front wheel 14 is still restricted by the wheel brake 46. Here, when the vehicle is stopped only by the parking clutch brake 25 without providing the wheel brake 46, the vehicle is driven by the mechanical rotation play between the output shaft 20 of the transmission 12 and the front wheels 14. There may be a slight swing back in the opposite direction. However, in the present embodiment, since the rotation of the front wheels 14 is kept regulated by the wheel brake 46 when the vehicle stops, the run-back of the vehicle can be prevented.

Hereinafter, embodiments other than the above embodiments embodying the present invention will be described as other examples. In the first embodiment, a wheel brake 46 is provided which is activated by hydraulic oil supplied by the master cylinder by a brake depression operation of the brake pedal 33, and braking of the vehicle is not connected by the shift position Ps of the shift lever 37. The clutches 21 and 22 and the wheel brake 46 may cooperate with each other. In this case, it is possible to suppress early wear of the clutches 21 and 22 due to braking, and to extend the inspection and maintenance time in the transmission 12.

In the first embodiment, the shift lever 3
The clutches 21 and 22 that are not connected by the shift position Ps 7 and the parking clutch brake 25 may cooperate to perform braking of the vehicle. In this case,
Early wear of the clutches 21 and 22 and the parking clutch brake 25 can be suppressed, and the inspection and maintenance time in the transmission 12 can be extended.

In the second embodiment, the wheel brake 46 may be omitted, and the vehicle may be braked only by the parking clutch brake 25 having a large capacity. In this case, the number of parts and the number of assembling steps can be reduced by the amount corresponding to the wheel brake 46, the master cylinder, and the like.

In the second embodiment, in addition to the wheel brake 46 and the parking clutch brake 25, the vehicle may be braked by the clutches 21 and 22, which are not connected by the shift position Ps of the shift lever 37. Good. In this case, it is possible to suppress early wear of the parking clutch brake 25 and extend the inspection and maintenance time in the transmission 12.

In the first embodiment, when the rotational acceleration α is equal to or more than the rotational acceleration determination value α0, the clutch pressure Prcl of the braking side, for example, the clutch 22 is always set to the initial brake clutch pressure Prcl 0 (Pbrk, W). You may make it. Similarly, in the second embodiment, the rotational acceleration α
Is greater than or equal to the rotational acceleration determination value α0, the brake clutch pressure Pbcl of the parking clutch brake 25 may always be set to the initial brake clutch pressure Pbcl 0 (Pbrk, W). Also in each case, it is possible to prevent the front wheels 14 from slipping on the road surface during braking during traveling.

In the first embodiment, the rotation acceleration reference value αmode may be a fixed value that does not change, and the rotation acceleration reference value αmode may be made to match the rotation acceleration determination value α0. In this case, when the rotational acceleration α becomes less than the rotational acceleration determination value α0 and then becomes the rotational acceleration determination value α0 or more again, the initial brake clutch pressure Prcl 0 (Pbr
k, W), the deviation Δα of the rotational acceleration α from the rotational acceleration determination value α0 when the rotational acceleration is smaller than the rotational acceleration determination value α0
, The brake clutch pressure Prcl (Pbrk, W) reduced by an amount corresponding to the added value ΣΔα is set to a new clutch pressure Prcl instead of “0”.

Similarly, also in the second embodiment, the rotational acceleration reference value αmode may be set to a fixed value that is not changed, and the rotational acceleration reference value αmode may be made to match the rotational acceleration determination value α0.

In the first embodiment, when the rotational acceleration α is equal to or larger than the rotational acceleration determination value α0, the clutch pressure Prcl of the braking side, for example, the reverse clutch 22 is changed to the initial brake clutch pressure Prcl 0 (Pbrk, W). When the rotational acceleration α is smaller than the rotational acceleration determination value α0, the clutch pressure Prcl is set to a fixed value sufficiently smaller than the initial brake clutch pressure Prcl 0 (Pbrk, W). The non-braking brake clutch pressure Prcl without setting the braking force to “0” may be used.

Similarly, in the second embodiment, when the rotational acceleration α is equal to or larger than the rotational acceleration determination value α0, the brake clutch pressure Pbcl of the parking clutch brake 25 is changed to the initial brake clutch pressure Pbcl 0 (Pbrk, W). When the rotational acceleration α is smaller than the rotational acceleration determination value α0, the brake clutch pressure Pbcl is set to a fixed value sufficiently smaller than the initial brake clutch pressure Pbcl 0 (Pbrk, W). Alternatively, the non-braking brake clutch pressure Pbcl without setting the braking force to “0” may be used.

In the second embodiment, in the control of the parking clutch brake 25 for braking the vehicle in cooperation with the wheel brake 46, the vehicle speed V is determined to be the low-speed braking determination value V1.
In the following condition, the brake clutch pressure Pbcl of the parking clutch brake 25 may be controlled when the rotational acceleration α is smaller than the rotational acceleration determination value α0, as in the case where the rotational acceleration is equal to or greater than the rotational acceleration determination value α0. . Also in this case, the vehicle can be stopped smoothly without jerking just before stopping.

Similarly, in the case where the clutch 22 (21) on the side that is not connected during running and the wheel brake 46 are braked in cooperation, the clutch 22 (21) on the side that is not connected during running and the clutch clutch brake for parking are used. 25 and the parking clutch brake 25
Brake only, or the clutch 22 (21) and the wheel brake 4 that are not connected during running.
6 and the parking clutch brake 25 may cooperate to perform braking. In each case, the vehicle can be stopped smoothly without jerking just before stopping.

In the first and second embodiments, instead of setting the rotational acceleration determination value α0 to a value for determining that the front wheel 14 has been locked, the vehicle at the time of braking due to slippage of the front wheel 14 is set. Front wheel 14 when the directional stability of the vehicle decreases
May be set to a value for determining the predetermined slip ratio. In this case, slippage of the front wheels 14 during braking during traveling can be further suppressed, and the directional stability of the vehicle can be increased.

An industrial vehicle provided with a travel control device is an industrial vehicle that inputs the driving force of an engine to a transmission via a torque converter and switches the rotation direction of driving wheels by switching connection of a clutch in the transmission. Not limited to a forklift, for example, a tractor shovel, a shovel loader, or the like may be used.

Hereinafter, in addition to the inventions described in the claims, the technical ideas grasped from each of the above-described embodiments or other examples will be described together with their effects. (1) An industrial vehicle provided with the travel control device for an industrial vehicle according to any one of claims 1 to 7. According to such a configuration, it is possible to improve the driving operability by eliminating the need for the clutch operation, and to suppress the slip of the drive wheels on the road surface during braking without increasing the number of new components.

[0121]

According to the first to eighth aspects of the present invention, the switching operation of the direction switching operation member automatically performs the connection / disengagement operation of the clutch for transmitting the power, and adds a new component member. It is possible to suppress slippage of the drive wheels on the road surface during braking during traveling without increasing the number of wheels.

According to the inventions set forth in claims 2 to 8, braking can be performed by the forward and reverse clutches in the transmission, and the invention can be applied to a vehicle without a parking clutch brake.

According to the third to eighth aspects of the present invention, braking can be performed by a parking clutch brake different from a forward clutch and a reverse clutch, and early wear caused by braking of the reverse clutch is suppressed. can do.

According to the fourth to eighth aspects of the present invention, the vehicle can be stopped smoothly without jerking immediately before stopping. According to the fifth to eighth aspects of the present invention, the vehicle can be braked while the slip does not increase even if the friction coefficient of the road surface to be braked and the mounted tires become small.

According to the sixth to eighth aspects of the present invention, it is possible to adjust the deceleration with respect to the brake operation amount during braking. According to the invention described in claim 7 or 8, even when carrying a load whose load is unknown, the vehicle can be stopped at the traveling distance predicted by the driver.

According to the eighth aspect of the present invention, early wear of the clutch brake can be suppressed. Further, it is possible to prevent the vehicle from swinging back when stopped.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a forklift traveling control device according to a first embodiment.

FIG. 2 is an electric block diagram of a travel control device.

FIG. 3 is a map of reference clutch pressure-brake pressure of a reverse clutch.

FIG. 4 is a map of a correction coefficient and a load.

FIG. 5 is a time chart of a brake pressure, a rotational acceleration of a drive wheel, and a clutch pressure of a reverse clutch during braking.

FIG. 6 is a flowchart of a braking control process.

FIG. 7 is a schematic configuration diagram of a travel control device according to a second embodiment.

FIG. 8: Reference clutch pressure of parking clutch brake
Brake pressure map.

FIG. 9 is a graph of braking force-brake pressure.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Engine, 11 ... Torque converter, 12 ... Transmission, 14 ... Front wheel as a drive wheel, 15 ... Throttle actuator, 21 ... Forward clutch as brake means in the first embodiment, 22 ... Reverse clutch , 23 ... an electromagnetic proportional pressure control valve as a traveling electromagnetic pressure control valve and a braking electromagnetic pressure control valve in the first embodiment, 24 ... the same electromagnetic proportional pressure control valve, 25 ... second
A parking clutch brake as a braking means in the embodiment; 26 ... an electromagnetic proportional pressure control valve as a braking electromagnetic pressure control valve in the second embodiment; 29 ... a gear constituting driving wheel rotational speed detecting means; Reference numeral 30 denotes a magnetic sensor, reference numeral 33 denotes a brake pedal as a brake operating member, reference numeral 35 denotes an emulator which constitutes a brake operating force detecting means, reference numeral 36 denotes a pressure sensor, and also reference numeral 37 denotes a shift lever as a direction switching operating member and reference numeral 38 denotes a direction detecting means. A shift position switch as a reference; 39 a mode switch constituting deceleration setting means; 44 a pressure sensor as a load detection means; 46 a wheel brake; 54 a clutch control means; a drive wheel rotational speed detection means; ,
Microcomputer as rotational acceleration calculating means constituting deceleration setting means, 55 ... clutch control means, drive circuit constituting brake control means, Pfcl ... clutch pressure as brake pressure in the first embodiment, Prcl
... Similar clutch pressure, Pbcl ... Brake clutch pressure as brake pressure in the second embodiment, V ... Vehicle speed,
V1: low-speed braking judgment value, α: rotation acceleration, α0: rotation acceleration judgment value, αmode: rotation acceleration reference value, Δα: deviation, ΣΔα: deviation addition value.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) G01P 3/56 F16D 25/14 650 F term (reference) 3D041 AA12 AA30 AA47 AB07 AC01 AC09 AC18 AD02 AD10 AD23 AD31 AD41 AD50 AD51 AE04 AE39 AE41 3D045 AA06 EE21 FF42 GG01 GG10 GG11 GG27 GG28 3D046 AA06 BB17 GG02 GG05 GG06 HH02 HH05 HH22 HH26 HH39 JJ04 3F333 AA02 AB13 FA20 FA31 FB10 GE03 GB04 GE04 GB04

Claims (8)

[Claims] 1. A torque converter to which the driving force of an engine is input, a forward clutch and a reverse drive which input a driving force of the engine via the torque converter and adjust a connection state by changing a clutch pressure. A transmission that outputs the driving force via one of the clutches, and a switching position of a direction switching operation member that is switched to connect and disconnect one of the two clutches. Direction detecting means, a traveling electromagnetic pressure control valve provided for each of the clutches, and for controlling the clutch pressure to adjust the connected state of the clutch between a completely connected state and a disconnected state, and the switching position And a clutch control means for controlling each of the traveling electromagnetic pressure control valves in accordance with the control and controlling the clutch pressure to completely connect or disconnect the respective clutches. A travel control device for a vehicle, comprising: a brake means capable of braking the vehicle with a braking force corresponding to a brake pressure of supplied hydraulic oil; a braking electromagnetic pressure control valve for adjusting the brake pressure; and a brake operation member. Brake operation force detection means for detecting a brake operation force when a brake is operated, drive wheel rotation speed detection means for detecting a rotation speed of a drive wheel rotationally driven by a drive force output from the transmission, A rotational acceleration calculating means for sequentially calculating a rotational acceleration of the drive wheel from the drive wheel rotational speed; and, based on the brake operating force, the brake means brakes with a larger braking force as the brake operating force increases. Controlling the brake pressure via the braking electromagnetic pressure control valve, and controlling the rotational acceleration so that the driving wheel slips on a road surface. Brake control means for controlling the brake pressure such that the braking force of the brake means is smaller than the braking force based on the brake operation force when the rotational acceleration is less than a preset rotational acceleration determination value for the determination. Traveling control device for industrial vehicles. 2. The travel control device for an industrial vehicle according to claim 1, wherein the brake means is not connected to one of the forward clutch and the reverse clutch based on a switching position of the direction switching operating member. A travel control device for an industrial vehicle, wherein the clutch is a clutch, and the braking electromagnetic pressure control valve is the traveling electromagnetic pressure control valve that controls a clutch pressure of the clutch. 3. The travel control device for an industrial vehicle according to claim 1, wherein the brake means is provided separately from the forward and reverse clutches, and controls the movement of the vehicle by braking the rotation of drive wheels. A possible parking clutch brake, wherein the electromagnetic pressure control valve for braking is provided separately from the electromagnetic pressure control valves for traveling, and a travel control of an industrial vehicle for adjusting a brake clutch pressure of the parking clutch brake. apparatus. 4. The travel control device for an industrial vehicle according to claim 1, wherein the brake control unit determines that the vehicle speed is equal to or less than a predetermined low-speed braking determination value. In the state, the travel control device for an industrial vehicle controls the brake pressure when the rotational acceleration is less than the rotational acceleration determination value, as in the case where the rotational acceleration is equal to or greater than the rotational acceleration determination value. 5. The travel control device for an industrial vehicle according to claim 1, wherein the brake control unit is configured to determine whether the rotational acceleration is less than the rotational acceleration determination value. The brake pressure is a non-braking brake pressure for bringing the brake means into a non-braking state, and when the rotational acceleration again becomes equal to or greater than the rotational acceleration determination value, the brake pressure is set to at least the rotational acceleration determination value. The non-brake brake pressure is smaller than the brake pressure corresponding to the brake operation force by a magnitude corresponding to the sum of the deviation of the rotational acceleration from the rotational acceleration reference value when the rotational acceleration is less than the preset rotational acceleration reference value. Travel control device for industrial vehicles with a size close to 6. The travel control device for an industrial vehicle according to claim 5, further comprising deceleration setting means for setting the rotational acceleration reference value in accordance with a setting state for setting deceleration during braking. Travel control device for industrial vehicles. 7. The traveling control device for an industrial vehicle according to claim 1, further comprising a load detection unit configured to detect a load, wherein the brake control unit detects the load. The brake pressure is controlled via the braking electromagnetic pressure control valve so that the brake means brakes with a larger braking force as the brake pressure increases, and when the rotational acceleration is less than the rotational acceleration determination value, the brake A travel control device for an industrial vehicle that controls the brake pressure such that the braking force of the means is smaller than the braking force based on the brake operation force and the loaded load. 8. The travel control device for an industrial vehicle according to claim 1, wherein the brake operation member is operated by a brake operation, and the braking operation is performed according to the brake operation force. A travel control device for an industrial vehicle, comprising: a wheel brake for braking the drive wheel with power, wherein the brake means brakes the vehicle in cooperation with the wheel brake.